The present invention is with respect to remote control systems for constructional machinery, more specially in the form of concrete pumps with a distribution mast, making use of a portable console for use as a command controller and having a number of circuits which have switches for producing different control functions and furthermore are each joined with a multi-contact connector. There is furthermore a transmitter means and a receiver means which has an electrical distributor for the operation of solenoid valves and a plug connector for transmission means.
In the prior art concrete pumps, forming the preferred field of use of the present invention, have as a rule been controlled by changing their speed of turning so that the rate of concrete supply may be changed to be in keeping with filling up of the formwork with concrete and furthermore the direction of pumping is reversible so that the supply pipe may be not only be filled with concrete at the start of an operation but at the end of the operation it may be cleared of concrete. The distribution mast is mostly mounted on a column with a turntable or the like and made up of different sections that are able to be folded and hinged by hydraulic drives, more specially in the form of rams, independently of each other so that concrete coming out of the top end of mast may be supplied at different points at different levels and with different horizontal distances therebetween. Although the invention may be used in connection with other construction machinery with a greater or smaller number of control functions, as for example earth moving machines and more specially excavators, the present account of the invention is limited to the preferred use, that is to say in connection with concrete pump systems.
Known radio remote control systems with wireless transmission of the control commands are generally based on pulse modulation. In this case the receiver fitted on the construction machine is responsible for supplying the necessary control voltage as the output signal. In this respect trouble through interference from other plant is likely, more specially from other radio signals and furthermore as is caused by strong magnetic fields, that are produced near high voltage distribution lines because of their field strength. The outcome of such interference may well be uncontrolled motion of the boom or mast so that workers are put in danger and materials are likely to be damaged. Radio control systems using transmission by digitally encoded RF messages or alternatively signal transmission with light guides have been put forward in the prior art at some time and may take care of such shortcomings. However in their present form they are not such that they might be used with constructional machinery.
On the other hand remote controls with a multi-core cable as a transmission connection have come to be used on a large scale for construction machinery, more specially in the more limited field of the present invention. Such cables are joined up with the controller for generating the commands and with the receiver means using multi-contact connectors. This may be said to be the starting point of the present invention. Such known remote control systems have been selected more specially because one may be certain that no undesired commands are generated or transmitted. Generally the cable has one channel or core for each control function. However under certain working conditions such systems have serious shortcomings.
Because the machine operator is not able to keep to one position in relation to the machine he is controlling and has to take the command generator round with him, the cable will necessarily be dragged through buildings and the like. In the case of rough conditions on the building site the cable will then have to be taken through and past many obstacles, as for example open shafts in the building, windows, staircases and like parts of the structure if the machine operator is to be able to take up a position in which full observation of the concreting operation is possible. Furthermore his life will be in danger if for example the distribution mast, that has a large range of motion, is being moved about near high voltage lines where there is some chance of discharge of electricity thereto.